Valve-gear



(No Model.)

M. GREENWOOD.

' VALVE GEAR.

110. 445,810. Patented Peb.3,1891.

INVENTORE- Me! W,

WITNESSES:

UNITED STATES PATENT OFFICE.

MICHAEL GREENWOOD, OF BELLEVUE, DELAWVARE, ASSIGNOR TO THE; HALL STEAM PUMP COMPANY, OF PLAINFIELD, NEIV JERSEY.

VALVE-GEAR.

SJPEGIFICATION forming part of Letters Patent No. 445,810, dated February 3, 1891. Application filed December 21, 1889- Serial No. 334.6% (No model.)

To all whom it may concern:

Be it known that 1, MICHAEL GREENWOOD,

a citizen of the United States, residing in Bellevue, in the county of New Castle, State 5 of Delaware, have invented certain new and useful Improvements in Valve-Gear, of which the following is a specification.

This invention relates to that class of valvegearing for steam-engines wherein the main slide-valve (or valves in the case of a compound engine) controlling the ingress and egress of steam to the power-cylinder (or cylinders) is steam-actuated, and wherein the steam for actuating the main slide-valve (or valves) is controlled by an auxiliary slidevalve operated by mechanical connection with a moving part of the engine. These engines have been constructed with a power-cylinder, its steam-chest having a main sliding valve, an auxiliary cylinder having a steam-actuated piston which is mechanically connected with the main sliding valve, and the steamchest and valve for said auxiliary cylinder. The present improvements relate to engines of this character; and they consist in the construction and arrangement of the two cylinders with their steam-chests and the connections between the auxiliary piston and the main valve, whereby compactness in the engine is secured without interfering with the proper action of the main valve.

The improvements are illustrated in the accompanying drawings, in which Figure 1 is a side elevation of a compound steam pumping-engine having the present improvements. Fig. 2 is a plan view thereof. Fig. 3 is a vertical cross-section in a plane indicated by the line 3 3 in Figs. 1 and 2, and Fig. 4 is a view in the nature of a diagram showing the mechanical connections between the main valves and their controlling-piston.

A is the high-pressure powereeylinder. I3 is the piston-rod thereof.

is thelow-pressure power-cylinder. D D are the two piston-rods thereof.

E is the cross-head connecting the three piston-rods.

F is the valve-chest of the higlrpressure cylinder. Gr is the reciprocating valve there- 50 in, an ordinary D slide-valve being shown.

II is the valvechcst of the low-pressure engine. I is the valve therein, an ordinary D slide-valve being shown, and J is the reciprocating valve-rod common to both the valves G and I. The valve-rod is connected directly to the valves in the usual manner, so thatthe valves always move'with the valve-rod, and there is no relative reciprocation or longi tudinal movement between the valve rod and either of the valves.

K is an auxiliary steam-cylinder, in which works the main-valveactuating piston L, and M is the valve-chest thereof, in which works the auxiliary valve N. The auxiliary cylin der is located alongside the high-pressure cylinder, but in a different horizontal plane, so that while the axis of the auxiliary cylinder is above that of the high-pressure oylinderit is nevertheless below the valve-chest F of the high-pressure cylinder. The auxiliary valvechest M is alongside the auxiliary cylinder andin the same horizontal plane. Owing to this arrangement compactness is secured.

The auxiliary valve N is rigidly connected to its valve-rod O, which reciprocates in a right line, being guided by its stuffing-box a and by its outer end sliding in a fixed bracket Z), which in turn is supported by one of two fixed brackets c c on opposite sides of the engine. Journaled in these two brackets is a cross rock-shaft P, which is rocked by alever Q, having slotted connection with the crosshead E. A crank-arm (Z on'the rock-shaft is connected by a bifurcated link c with a sleeve f, embracing and sliding on the valve-rod O between two fixed tappets g g thereon. The oscillation of the rock-shaft causes the sleeve f to come alternately in contact with the tappets, and so move the valve-rod O and shift the auxiliary valve N. The movement of the 0 auxiliary valve causes the main-valve-actuating piston L to move back and forth in the auxiliary cylinder K. The main-va1ve-actuating piston L has a piston-rod R extending out through a stutfing-box in the cylinder- 5 head, and it is connected by a link S with one end of alever T, which is fulcrumed 011 a fixed axis on a bracket U, rigidly fixed to the valvechest F of the highpressure cylinder. The other end of the lever T is connected by a link :00 V with the valve-rod J of the main slide-valve. The pivotal point of the linkV on the lever Tis nearer the fulcrum of the lever than the pivotal connection between the lever and the link S, so that a long movement of the mainvalve-operating piston will produce a short movement of the main valves. Preferably the points of connection are such that the extent of movement of the main valves will be about one-third that of the valve-actuating piston.

In a common type of steam pumpingengines the main valve has been directly connected with its actuating-piston, and the latter is moved suddenly on the admission of the steam, so that the main valve has been shifted suddenly, thus prod ucing' a shock on the main piston, which is communicated to the Water piston and valves of the pump, thereby causing a pounding or Water-hammer. \Vith the described improvements, however, a quick movement of the actuating-piston causes a slow movement of the main valves, so that the main pistons gradually slow down as they approach the ends of their strokes. This slow and steady movement of the main valve allows the pump-valves to open and close quietly, thereby avoiding shocks and pounding.

Owing to the relative positions in different horizontal planes of the auxiliary cylinder and the valve-chest of the high-pressure cylinder, the lever T occupies an angular position, which is advantageous, since it permits the employment of a longer lever than would be possible if the cylinder and valve-chest were compactly arranged in the same vertical or horizontal plane.

I claim as my invention The steam-cylinder and steam-chest of a steam-engine and an auxiliary cylinder arranged alongside said steam -cylinder and steamchest, the three being in three different horizontal planes, the auxiliary cylinder occupying the intermediate plane, in combination with the main valve in said steam-chest and its valve-rod, the main-valve-actuating piston in said auxiliary cylinder and its piston-rod, a fixed bracket on said steam-chest, an an gularly-arrang'ed lever fulcrumed nearer one end than the other on a fixed axis in said bracket, a link connecting the short end of said lever with said valve-rod, and a link connecting the long end of said lever with said piston-rod, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

MICHAEL GREENVOOD.

Witnesses:

GEORGE H. FRASER, J NO. E. GAVIN. 

